Wearing Screed / Structural Topping Over Insulation

[Nick]

Hi All

 

Currently looking at a potential conversion that has a good condition, but uninsulated floor slab.

 

I've always wanted a smooth consistent finish across the whole ground floor, and had imagined that would be the floor slab itself if we were building a passive slab from new. Now that this opportunity has come up, I'm looking for something that will do the job of screed in transferring heat from UFH pipes and levelling off the floor, but will be OK installed on top of 150mm PIR as a final floor finish.

 

Searches have brought up the idea of wearing screed / structural topping, but from what I've read, they shouldn't be used over insulation?

 

If i were to go for a thinner concrete pour over the insulation / UFH, would I have issues getting a smooth finish (guessing 50-60mm concrete would need some fibre reinforcing to avoid cracks and would be too thin to power float)?

 

Any suggestions on the simplest solution?